Shouting at the ocean with pebbles in my mouth since 2008. The subjects of this blog include forensics, the war-on-terror detainees, the Duke lacrosse case, the Knox/Sollecito case, and the academic world as it intersects the political. It will sometimes examine issues of particular interest to Wilmington, NC and the University of North Carolina at Wilmington.

Tuesday, December 2, 2014

Gary Leiterman and DNA contamination

Jane Mixer was initially thought to be the
victim of a possible serial killer, John Norman Collins.Jane Mixer was murdered in 1969 near Ann Arbor, MI, but the
DNA testing was done until 2002, a gap of approximately 33 years.One item of evidence from the Mixer
case showed DNA from John Ruelas, and several locations (on some panty hose and
a towel) showed DNA from Gary Leiterman.Despite the fact that the state had no other evidence against Leiterman,
he was convicted of her murder in 2005.John Ruelas was never charged.

A drop of blood from Mixer’s hand was
preserved, and DNA from John Ruelas was found.The prosecutor believed that the blood was from John Ruelas,
but he did not offer a satisfactory explanation of how his blood came to be
there.Because Ruelas was four
years old at the time of the murder and lived about forty miles away, the
possibility that his DNA arrived instead via contamination must be considered.As defense expert witness Theodore
Kessis wrote, “The unexpected and never accounted for finding of John Ruelas’
profile on evidence in the Mixer case clearly demonstrates the proposition that
contamination can and does occur between samples from different cases.”

The presence of Ruelas’ DNA is most easily
explained by the fact that samples from John Ruelas were also processed in the
crime laboratory of the State Police of Michigan contemporaneously with the samples from the Mixer murder.But can the absence of Mixer’s DNA in
the blood drop also be explained?In 2004 C. Peel and P. Gill (“Attribution of DNA profiles to body fluid
stains,” International Congress Series 1261, pp. 53-55) performed a series of
experiments, in which a good DNA shedder handled the substrate (cotton or
glass) for a blood stain, either before or after the blood from a different
individual was placed on the substrate.The blood was either diluted or the stain had been left to sit for some
months, allowing for possible DNA degradation over time.They used leucomalachite green as a presumptive
test for blood. Peel and Gill wrote, “…the
more dilute or degraded the stain, the higher the contribution of the substrate
handler’s DNA to the resulting profile.A positive presumptive test could be obtained from samples when a
profile originating from the body fluid was no longer detectable.”Although it is tempting to associate
the DNA that one finds in a stain to that stain, such an association is
occasionally in error.In some
cases substrate controls can be helpful in determining whether or not DNA is
associated with a particular stain.

It is essentially 100% certain that
Ruelas’s DNA arrived on the items from the Mixer case via contamination,
although the exact route is unclear.Gary Leiterman’s DNA was also in the laboratory at
that time. No body fluid could be
associated with Leiterman’s DNA associated with evidence from the Mixer
case.Sub-source DNA such as this is weaker in
probative value than DNA associated with a particular tissue or body fluid. Taking these facts and ideas into
consideration, Leiterman’s DNA probably also arrived via contamination.

A second line of evidence also implies that contamination is the most likely explanation. A lab worker performed a negative control experiment during
the time that a sample from the panty hose was being tested. The negative controls will only show the
presence of DNA in an electropherogram if DNA has been introduced unexpectedly
into the experiment. Theodore
Kessis wrote, “Review of the electropherograms associated with this negative
control sample (NEG 041902) reveals that it was contaminated, a fact that cannot
be disputed since Dr. Milligan himself labeled it with a note indicated as much
(Appendix 8 – Electropherogram sample NEG 041902).Remarkably, Dr. Milligan stated in his 7/15/02 testimony
that no contamination events had occurred during the course of his testing and
that if any had, he would have documented them in his reporters (p. 141-21 and
142-4).Equally difficult to
rectify here is the fact that when asked if he had ever committed an error, Dr.
Milligan’s replied that he could never recall making one.”CBS News reported that, “Lab supervisor
Jeffrey Nye says he retraced every step and he does not believe there is any
issue of contamination. ‘No issue whatsoever,’ he says.” This is an astonishing statement.

This lack of disclosure of a contamination
event and a similar occurrence in the Adam Scott case (Peter Gill, Misleading
DNA Evidence, Academic Press, 2014, p. 22) demonstrates that one cannot implicitly rely upon a
laboratory to report accurately the results of negative control reactions.Yet this is valuable information; a jury might choose to discount
testimony from a lab if it knew contamination had happened.It is also worth recalling what William
Thompson noted in “Tarnish on the Gold Standard,” which is that the some
laboratory workers tamper with negative controls in various ways.For these reasons full disclosure of
the negative controls in the form of raw (meaning unprocessed) data is the best
course of action for a judicial system.Students of the Knox/Sollecito case will not be surprised to learn that
the position of the Michigan State Police crime laboratory was foursquare against disclosure of the raw data.Professor Thompson wrote, “The Deputy
Director of the Michigan State Police issued a statement on May 12, 2005
opposing ‘the allowance of releasing raw electronic data for subsequent
manipulations using software and parameters not validated by the Michigan State
Police Forensic Laboratory’ and declaring that ‘it is the position of the
Michigan State Police Forensic Science Division that any release of this (sic)
data for processing with non-validated parameters is tantamount to evidence
tampering.’”26This is
a self-evidently nonsensical position, and it also forces one to ask why the
processing parameters chosen by a forensic laboratory are necessarily the
optimal ones.

Conclusions

The DNA evidence against Gary Leiterman is
compromised so completely by the presence of the DNA from John Ruelas that it
scarcely should be called evidence at all. Exactly how their DNA came to be on items of evidence from the murder of Jane Mixer is not known.Dr. Theodore Kessis commented on the Benjamin
LaGuer case: “It is highly improbable that any given forensic DNA
laboratory will take it upon itself to contact its accrediting bodies or the
press and state for the record how often they make mistakes… To best understand
the weaknesses associated with DNA testing we must rely upon the empirical, the
occasions in which such deficiencies are revealed either by the press or
internal review of a lab’s documentation of such problems by a defense expert. A close look at either reveals that
indeed many instances of DNA testing errors have lead to the false conviction
of individuals.”Regrettably, even
the sworn testimony of laboratory personnel may be seriously in error, as in
the Leiterman case.Nor can a jury
be counted upon to accurately weigh the odds of contamination.Quite the contrary, juries
sometimes discount alibi evidence, such as the Farah Jama case, or the fact
that the defendant lived in one city and claimed never having been to the city where the crime occurred, as happened in the Adam Scott case. Both cases are now generally believed to be instances of DNA contamination.

I remember seeing the Investigation Discovery program on this case. Obviously, the whole trial was not shown in a sixty minute program, but while the Ruelas DNA was mentioned as being present and contamination was possible (though denied by the prosecutor). I did not hear the additional information regarding Ruelas being charged with a crime and evidence from that crime being processed in the same lab where the Mixer murder evidence was processed. Throw in the facts that Leiterman's evidence from his arrest for a prescription drug offense AND that Jane Mixer's own samples showed severe degradation, while DNA found from Leiterman and Ruelas showed no such degradation...the odds of this being something other than contamination must be astronomical. Why is Mr. Leiterman still in prison...

Ruelas was only four years old at the time that Mixer was murdered, and was not charged with anything regarding her murder. His DNA was tested because he had murdered someone as an adult. The prosecutor's notion that he had a nosebleed at the scene of the crime is risible. I recall some time ago trying to track down exactly when Ruelas's and Leiterman's reference samples were in the lab. My recollection is that with Ruelas it was clear that his sample was exactly contemporaneous with the items from the Mixer murder. However, I had a slightly harder time nailing down Leiterman's sample. It is also noteworthy that the lab had indeed experienced contamination, yet they denied it at the trial. This points out a weakness of the American system, which is that the jury's verdict is treated as near sacrosanct.

Erin Murphy wrote, "Leiterman's sample came into the laboratory on February 22, 2002; the evidence in Ruelas's case was processed the day before. Leiterman's sample was first analyzed between July 17 and July 23; Ruelas's reference sample was submitted on July 19 then sent to an outside lab for testing. The Mixer evidence was processed at the lab between March 26, 2002, and April 9, 2002." p. 57, "Inside the Cell: The Dark Side of DNA"

Hard to sympathize with someone who drugged a foreign exchange student who was living with his family, then posed her (in the exact same pose that Jane Mixer was placed in by her murderer) and took pictures of her.

He also bragged that, with his access to pharmaceuticals, he could assault any woman he wanted to.

I agree that Leiterman's actions don't engender sympathy. One news report stated that, "The images showed the girl - drugged unconscious - lying on Leiterman's bed with her clothing pulled back to expose her genitals. Authorities said the pose was an eerie echo of Jane Mixer's corpse." Another one stated that, "Police noted that the positioning of the clothing was similar to the way Mixer was found. The girl told investigators she did not remember taking the photos." Based on just these two reports, I would say that you are overstating your case: "exact same" is a stronger claim than "similar." With Ruelas' DNA there can be no doubt that there was contamination. Given this evidence, what are your grounds for ruling out that Leiterman's DNA arrived in the same way? The prosecutor's claim that it was Ruelas' blood is a good example of the association fallacy, as Peter Gill has called it.

About Me

I am a biochemist who specializes in the chemical modification of proteins and the synthesis of potential enzyme inhibitors. I am particularly interested in the chemistry of phosphorus and sulfur as it can be applied to biochemical problems.